Japanese Utlity Model Publication No. 1-24852 discloses an ampere-switching mechanism for a battery charger for charging batteries with different current ratings. This mechanism includes plural switches located below the bottom of a charging hole and push buttons projecting from the respective switches into the charging hole. Each switch is designed to meet the particular current rating of one of the batteries for which the battery charger is intended. The switching mechanism also includes recesses formed in the bottom of each rechargeable battery which accommodate the irrelevant push buttons therein, when the battery is set down into the charging hole, to keep the irrelevant switches from being actuated. Thus, when a rechargeable battery is set down into the charging hole, the battery depresses only the switch designed to meet the current rating thereof.
It is possible to exactly imitate the foregoing ampere-switching mechanism to produce a voltage-switching mechanism for a battery charger for charging batteries with different volt ratings.
However, one of the drawbacks of the foregoing ampere-switching mechanism is that it requires the use of plural switches. Another drawback is that means specially designed for not actuating the irrelevant switches, i.e., the recesses to accommodate the irrelevant push buttons, are provided in all the batteries for which the battery charger is intended. A further drawback is that since the push buttons are located at the bottom of the charging hole, the switch is not actuated if one does not fully insert the battery, i.e., if he does not insert it all the way to the bottom of the charging hole. Another drawback is that if a foreign object is in one or both of the recesses of the battery, the irrelevant push button or buttons are depressed to actuate the irrelevant switch or switches.